Zeolitic materials, both natural and synthetic, have been demonstrated in the past to have utility as adsorbent materials and to have catalytic properties for various types of hydrocarbon conversion reactions. Certain zeolitic materials are ordered, porous crystalline metallosilicates having a definite crystalline structure as determined by X-ray diffraction, within which there are a large number of smaller cavities which may be interconnected by a number of still smaller channels or pores. These cavities and pores are uniform in size within a specific zeolitic material. Since the dimensions of these pores are such as to accept for adsorption molecules of certain dimensions while rejecting those of larger dimensions, these materials have come to be known as “molecular sieves” and are utilized in a variety of ways to take advantage of these properties.
Separation of small molecules such as carbon dioxide (CO2) and nitrogen (N2) or carbon dioxide (CO2) and methane (CH4) are important for many industrial processes. Since the dimensions of these small molecules are similar and the conditions for their separation can be quite demanding, the commercial development of suitable zeolitic materials has been a significant challenge.
There remains a need for new zeolites that can provide improved CO2 selectivity in gas separations.